Metal salts of phosphorus acids and process



3,401,185 METAL SALTS F PHOSPHORUS ACIDS AND PROCESS Norman A.Meinhardt, Lyndhurst, Ohio, assignor to The Lubrizol Corporation,Wicklitfe, Ohio, a corporation of Ohio No Drawing. Continuation-impartof application Ser. No. 468,965, July 1, 1965. This application June 16,1967, Ser. No. 646,482

18 Claims. (Cl. 260-4293) ABSTRACT OF THE DISCLOSURE An improvedprocess'for preparing metal salts of organic phosphinic and phosphonicacids and their thio analogs is described. The improvement consists ofcontacting the acid and the metal base in the presence of a catalyticamount of a carboxylic acid or salt thereof. The metal salts produced inthis manner exhibit greater heat and oxidation stability. These saltsare useful as additives for lubricants and fuels, as insecticides,pesticides, oreflotation agents, plasticizers, and the like.

This is a continuation-in-part application of Ser. No. 468,965, filedJuly 1, 1965, now US. Patent 3,347,790.

This invention relates to metal salts of organic phosphorus acids and toa process for preparing the same.

Metal salts of phosphorus acids such as phosphorothioic acids,phosphinic acids, and phosphonic acids find use in many applications.They are especially useful as additives in hydrocarbon compositions,plastics, resins, paints, lubricants, fuels, greases, etc. In mostapplications, an important consideration of the utility of such metalsalts is their resistance to degradation due to heat or oxidation. Agreat deal of effort has been devoted to the preparation of such metalsalts having improved thermal and oxidative stability.

Another consideration which relates to the commercial usefulness of suchmetal salts is the convenience and cost of the processes by which theyare produced. Thus, it is desirable to have processes which are capableof producing such metal salts in high yields and which can be carriedout under convenient process conditions.

It is, accordingly, an object of this invention to provide improvedmetal salts of phosphorus acids.

Another object of this invention is to prepare metal salts of phosphorusacids which have enhanced resistance to thermal and oxidativedegradation.

Another object of this invention is to prepare basic metal salts ofphosphorus acids.

Another object of this invention is to provide an improved process forpreparing metal salts of phosphorus acids.

These and other objects are accomplished by providing an improvement inthe process for preparing metal salts of phosphorus acids comprising thereaction of a Group II metal base with a phosphorus acid of thestructural formula nited States Patent 9 3,401,185 Patented Sept. 10,1968 Group I metals, Group II metals, aluminum, iron, nickel, cobalt,and copper.

The improved process of this invention is especially useful in preparingmetal salts of phosphinothioic acids and phosphonothioic acids. Theseacids are represented, respectively by the above formula wherein 1) bothR radicals are hydrocarbon or (2) one is hydrocarbon and the other is ahydrocarbon-oxy or --XH radical. The hydrocarbon group of these radicalscan contain up to about 200 carbon atoms and can be an alkyl, aryl,aralkyl, alkenyl, or cycloalkyl radical. These hydrocarbon groups maycontain one or more polar substituents such as ether, halo, nitro, andthe like. Such polar substituents usually account for no more than about10% by weight of the R radical. Preferably, at least one X is sulfur.

Phosphinothioic acids useful in the improved process of this inventioninclude ditolylphosphinodithioic acid,bis(dichlorophenyl)phosphinodithioic acid, di octylphenyl)phosphinodithioic acid, di(pentylphenyl)phosphinomonothioic acid,di(octylnaphthyl)phosphinodithioic acid, chlorophenylisopropylphenylphosphinomonothioic acid,di(isopropylphenyl)phosphinodithioic acid,di(ethylphenyl)phosphinodithioic acid, ditolylphosphinodithioic acid,diphenylphosphinodithioic acid, di(pheny1thiophenyl)phosphinodithioicacid, di(chlorophenyl)phosphinodithioic acid, dihexylphosphinodithioicacid, dioctadecylphosphinodithioic acid, dinaphthylphosphinodithioicacid, dibehenylphosphinodithioic acid, and dicyclohexylphosphinodithioicacid.

Suitable phosphonothioic acids are exemplified by those corresponding tothe above phosphinothioic acids wherein one of the hydrocarbon groupsattached directly to the phosphorus is replaced by the correspondinghydrocarbomoxy group or an --XH radical.

Mixtures of phosphorus acids are likewise useful in the process of thisinvention. They include the acids obtained by the reaction of aphosphorus sulfide such as phosphorus pentasulfide, phosphorussesquisulfide, or phosphorus heptasulfide with a hydrocarbon such as anolefin, olefin polymer, or liquid petroleum fraction. The product ofsuch reaction is usually a complex mixture containing predominantlyphosphinothioic acids and phosphonothioic acids. The reaction by whichsuch product is obtained is usually carried out at temperatures rangingfrom about C. to 300 C. or higher and involves mixing the hydrocarbonreactant with from about 0.5% to about 15% (by weight) of a phosphorussulfide. The reaction is Well-known in the art and conditions for itlikewise are well-known and need not be described in further detailhere. The hydrocarbon reactants useful in such reactions may be liquidpetroleum fractions having a boiling point of up to 600 F., olefinshaving from about 4 to 30 carbon atoms, and olefin polymers such aspolybutenes and polypropylenes having molecular weights ranging fromabout to about 100,000. Illustrative processes are disclosed in US.Patents 2,843,579, 2,962,493, 3,108,960, and 3,135,729.

The foregoing phosphorus acids are converted to their correspondingmetal salts by treatment with a basic metal compound such as the oxide,hydroxide, hydride, carbonate, bicarbonate, sulfide, methoxide, ethoxideor phenoxide of the metal such as lithium, potassium, sodium, aluminum,barium, calcium, strontium, magnesium, zinc, iron, cobalt, nickel,copper, or cadmium. The most frequently used basic metal compounds arethe oxides,

3 carbonates, and hydroxides of zinc, barium, calcium, an cadmium. Theimproved process of the invention is especially useful in preparing zincsalts.

As indicated previously, the improved process of this invention involvescarrying out the reaction of a phosphorus acid and a metal base in thepresence of a catalyst. The catalyst is a carboxylic acid having up toabout 10 aliphatic carbon atoms or a metal salt thereof. The acid maycontain up to about 3 carboxylic radicals. Specific examples of thesecatalysts include formic acid, acetic acid, propionic acid, butyricacid, benzoic acid, trimellitic acid, o-phthalic acid, succinic acid,maleic anhydride, 1,3- cyclohexanedioic acid, decylbenzoic acid, toluicacid, valeric acid, caproic acid, sebacic acid, Z-heptanoic acid,itaconic acid, caprylic acid, 4-nonanoic acid, 3-decanoic acid,phenylacetic acid, naphthoic acid, 9-phenylstearic acid, dibutylbenzoicacid, and the salts thereof of a metal indicated above. Where a metalcarboxylate is used as the catalyst, it is preferably the carboxylate ofthe same metal that is present in the metal salt of phosphorus acidproduced by the process of this invention. Metal carboxylates useful asthe catalyst are, for example, zinc acetate, calcium formate, bariumbutanoate, cobalt propionate, fer-. rous acetate, magnesium octanoate,cadmium naphthoate, cuprous acetate, nickel acetate, nickel phthalate,sodium acetate, potassium decanoate, lithium acetate, sodium benzoate,aluminum propionate, etc.

The alkanoic acids of up to 10 carbons and the aboveindicated metalsalts thereof comprise a preferred class of catalysts. Because of theireffectiveness and for economic reasons acetic acid and salts thereof areparticularly useful as catalysts.

A small amount of catalyst is effective to bring about the desiredresults of the process of this invention. Thus, the catalyst may bepresent in the reaction mixture at a concentration ranging from about0.001 to about 0.2 equivalent per equivalent of the phosphorus acid inthe reaction mixture. The preferred concentration of the catalyst is[from about 0.01 to 0.1 equivalent per equivalent of the phosphorusacid.

The catalyst is effective to promote a more complete utilization of thereactants in the process of this invention and it results also in ahigher yield of the desired product. Another advantage of the process ofthis invention is that the product so obtained has improved qualities asadditives for use in lubricants. The effectiveness of the catalyst inthese regards is especially noteworthy in the preparation of basic metalsalts of phosphorus acids by reacting a phosphorus acid with astoichiometrically excess amount (e.g., at least 1 and up to about 2equivalents per equivalent of the acid) of the metal base.

The term basic metal salts is used herein to describe salts wherein themetal is present in stoichiometrically greater amounts than thephosphorus acid radical. For instance, a normal or neutral zinc salt hastwo equivalents (i.e., one mole) of zinc per two equivalents (i.e., 2moles) of a phosphinic or phosphonic acid, whereas a basic zinc salt hasmore than two equivalents of zinc per two equivalents of the phosphorusacid.

The process of this invention, except for the use of the catalyst, canbe carried out under conditions which are known to be suitable for thereaction of a phosphorus acid and a metal base. Such conditions usuallyinclude a temperature of from about C. to the decomposition point of thereaction mixture. The preferred reaction temperature is within the rangefrom about 50 C. to about 200 C. The reaction can be effected simply bymixing the phosphorus acid and the metal base; it may be carried out inthe presence of a diluent or solvent which facilitates the control ofthe reaction temperature and the mixing of the reactants. Solventsuseful for this purpose are illustrated by benzene, toluene, xylene,naphtha, chlorobenzene, dioxane, nitrobenzene, hexane and mineral oil. I

A particularly convenient method of carrying out the process of thisinvention involves adding the metal base in small increments to amixture of the phosphorus acid and the catalyst in a solvent. Anothermethod involves adding the phosphorus acid to a mixture of the metalbase and the catalyst. Still another method involves preparing a slurryof the, metal base in a diluent and mixing the slurry with thephosphorus acid and the catalyst. Where the. catalyst is a metalcarboxylate, it may be formed in situ in the reaction mixture from thecorresponding carboxylic acid and the metal base present in the reactionmixture. I i

The formation of the metal salt by the process of this invention isusually accompanied by the formation of by-products such as water. Inmost instances the byproducts are separated from the metal salt bydistillation, filtration, evaporation, precipitation or any suchWellknown means. I v i The process of. this invention isuseful also forthe formation of metal salts of a mixture of the above-describedphosphorus acids or .mixtures of one or more of the above-describedacids and one or more other phosphorus acids such as phosphorothioicacids (e.g., dibutyl phosphorodithioic acid, diisooctylphosphorodithioicacid, diphenylphosphorodithioic acid) and up to about two equivalents,per equivalent of phosphorus acid, of a hydrocarbon-substituted succinicacid having at least about 50 aliphatic carbon atoms in the hydrocarbonsubstituent. The mixture, in many instances, consists of the two acidsin ratios of equivalents ranging from 0.1:1 to about 2:1. The sources ofthe hydrocarbon substituent in the succinic acid include principally thehigh molecular weight substantially saturated petroleum fractions andsubstantially saturated olefin polymers, particularly polymers ofmonoolefins having from 2 to 30 carbon atoms. The especially usefulpolymers are the polymers of l-monoolefins such as ethylene, propene,l-butene, isobutene, l-hexene, l-octene, 2-methyl-l-heptene,3-cyclohexyl-1- butene, and Z-methyl-S-propyl-l-hexene. Polymers ofmedial olefins, i.e., olefins in which the olefinic linkage is not atthe terminal position, likewise are useful. They are illustrated byZ-butene, 3-pentene, and 4-octene.

Also useful are the interpolymers of the olefins such as thoseillustrated above with other interpolymerizable olefinic substances suchas aromatic olefins, cyclic olefins, and poly-olefins. Suchinterpolymers include, for example, those prepared by polymerizingisobutene with styrene; isobutene with butadiene; propene isoprene;ethylene with piperylene; isobutene with chloroprene; isobutene withp-methyl styrene; l-hexene with 1,3-hexadiene; l-octene with l-hexene;l-heptene with l-pentene; 3-methyl-1- butene with l-octene;3,3-dimethyl-1-pentene with l-hexene; isobutene with styrene andpiperylene; etc.

The relative proportions of the mono-olefins to the other monomers inthe interpolymers influence the stability and oil-solubility of thefinal products derived from such interpolymers. Thus, for reasons ofoil-solubility and stability the interpolymers contemplated for use inthis invention should be substantially aliphatic and substantiallysaturated, i.e., they should contain at least about preferably at leastabout 95%, on a weight basis, of units derived from the aliphaticmono-olefins and no more than about 5% of olefinic linkages based on thetotal number of carbon-to-carbon covalent linkages. In most instances,the percentage of olefinic linkages should be less than 2% of the totalnumber of carbon-to-carbon covalent linkages.

Specific examples of such interpolymers include the copolymer of 95% (byweight) of isobutene with 5% of styrene; the terpolymer of 98% ofisobutene with 1% of piperylene and 1% of chloroprene; the terpolymer of95 of isobutene with 2% of l-butene and 3% of l-hexene; the terpolymerof 80% of isobutene with 10% of l-pentene and 10% of l-octene; thecopolymer of 80% of l-hexene and 20% of l-heptene; the terpolymer of ofisobutene with 2% of cyclohexene and 8% of propene; and the copolymer of80% of ethylene and of propene.

Another source of hydrocarbon radicals comprises saturated aliphatichydrocarbons such as highly refined high molecular weight white oils orsynthetic alkanes such as are obtained by hydrogenation of highmolecular weight olefin polymers illustrated above or high molecularweight olefinic substances.

The use of olefin polymers having molecular weights of about 750-5000 ispreferred. Higher molecular weight olefin polymers having molecularweights from about 10,000 to about 100,000 or higher have been found toimpart viscosity index improving properties to the final products ofthis invention. The use of such higher molecular weight olefin polymersoften is desirable. It will be noted that the hydrocarbon substituent inthe succinic acid likewise may contain inert polar groups. Thus, in thisrespect, it may be a radical which is substantially hydrocarbon incharacter, i.e., the polar groups are not present in proportionsufficiently large to alter the hydrocarbon character of the hydrocarbonsubstituent. The polar groups are exemplified by chloro, bromo, keto,ether, aldehyde, nitro, etc. The upper limit with respect to theproportion of such polar groups in a hydrocarbon substituent is usuallyabout 10% based on the weight of the hydrocarbon portion of thesubstituent.

The succinic acids are readily available from the reaction of maleicanhydride with a high molecular Weight olefin or a chlorinatedhydrocarbon such as the olefin polymer described hereinabove. Thereaction involves merely heating the two reactants at a temperatureabout 100200 C. The product from such a reaction is a succinic anhydridehaving a large hydrocarbon substituent. The hydrocarbon substituent maycontain olefinic linkages which may be converted, if desired, tosaturated, parafiinic linkages by hydrogenation. The anhydride may behydrolyzed by treatment with water or steam to the corresponding acid.It will be noted in this regard that the anhydride is equivalent to theacid insofar as its utility in the preparation of the product of A isconcerned. In fact, the anhydride is often more reactive than the acidand is often preferred.

In lieu of the olefins or chlorinated hydrocarbons, other hydrocarbonscontaining an activating polar substituent, i.e., a substituent which iscapable of activating the hydrocarbon molecule in respect to reactionwith maleic acid or anhydride, may be used in the above-illustratedreaction for preparing the succinic acid. Such polar substituents may beillustrated by sulfide, disulfide, nitro, mercaptan, bromine, ketone, oraldehyde radicals. Examples of such polar-substituted hydrocarbonsinclude polypropene sulfide, di-polyisobutene disulfide, nitratedmineral oil, di-polyethylene sulfide, brominated polyethylene, etc.Another method useful for preparing the succinic acids and anhydridesinvolves the reaction of itaconic acid with a high molecular weightolefin or a polarsubstituted hydrocarbon at a temperature usually withinthe range from about 100 C. to about 200 C.

Where the relative amounts of the reactants of the process of thisinvention are described in terms of chemical equivalents, the equivalentweight of a reactant is based on the number of the functional groupspresent within its molecular structure. Thus, the equivalent weight of aphosphorus acid is based on the number of phosof a Group II metal baseis one-half its molecular weight and the equivalent weight of a Group IImetal carboxylate is likewise one-half its molecular weight. Theequivalent weight of the carboxylic acid useful as the catalyst hereindepends on the number of the carboXylic acid radicals present in themolecule. To-illustrate, pphthalic acid (or phthalic anhydride) has twoequivalents per molecule, maleic acid (or maleic anhydride) has twoequivalents per molecule, trimellitic anhydride has three equivalentsper molecule and acetic acid has one equivalent per molecule.

The following examples illustrate the process of this invention:

EXAMPLE 1 A 45.5% toluene solution (695 grams) containing one equivalentof di(iso-propylphenyl)phosphinodithioic acid is added to a mixture of114 grams of toluene, 61 grams (1.5 equivalents) of zinc oxide, and 5.5grams (0.05 equivalent) of zinc acetate dihydrate while the reactionmixture temperature is maintained at C. The reaction mixture is heatedat 70 C. for one hour, heated to 40 C./ 10 mm. to distill oil? 300 gramsof toluene and 7 grams of water, diluted with toluene and filtered. Thefiltrate (588 grams) has a zinc content of 4.56%, a phosphorus contentof 3.65%, a sulfur content of 7.06%, and a Zn:P weight ratio of 1.25.Another experiment, similar to the above except that no zinc acetate isused, results in a product having a zinc content of 3.16%, a phosphoruscontent of 3.74%, a sulfur content of 7.26%, and a Zn:P weight ratio of0.845.

EXAMPLE 2 To 939 grams (1.13 equivalent) of a polyisobutene (molecularweight of 1000)-substituted succinic anhydride (having an acid number ofand prepared by chlorinating the polyisobntene, reacting the chlorinatedpolyisobutene with a 20% molar excess of maleic anhydride), there isadded 310 grams of mineral oil and 3.2 cc. of acetic acid. The mixtureis heated to 88 C. and mixed with 119 grams (2.93 equivalents) of zincoxide. The mixture is heated at 88-110 C. for two hours whereupon 820grams (1.1 equivalent) of di(chlorophenyl)phosphinodi thi-oic acid isadded to it at this temperature. The resulting mixture is then heated at100110 C. and then at C./20 mm. The residue is filtered. The filtrate(obtained in 94% of the theoretical yield) is found to have a phosphoruscontent of 1.97% and a zinc content of 5.4%. Another experiment siimlarto the above except that no acetic acid is used in the process resultsin a product (obtained in 95.9% of the theoretical yield) having aphosphorus content of 1.57% and a zinc content of 4.74%.

The effect of the acetic acid catalyst in increasing the utilization ofboth the phosphinic acid and Zinc oxide is shown in the following tablewhich reflects the results of seven preparations conducted undersubstantially identical conditions using the same reactants but withvariations in the ratio of reactants and the presence or absence ofacetic acid.

Amount of acetic Percent by weight of phosphorus and zinc 1SA=Polyisobutenyl-substitutdd succinic anhydride. 2 PA=Phosphinie acid.

7 EXAMPLE 3 (a) A di(alkylphenyl)phosphinothioic acid is prepared byreacting 3776 grams of a commercial mixture of alkylbenzenes having anaverage molecular weight of about 236, 622 grams of P 8 and 995 grams ofAlCl in a twelve-liter flask equipped with stirrer nitrate inlet tube,and reflux condenser. The mixture is heated to a temperature within therange of 105-110 C. for three hours while blowing the reaction mass withnitrogen. There after, the reaction mass is cooled to 70 C. and added to8 liters of water at room temperature over a twentyminute period. Anexothermic reaction results and the temperature increases to C. Thismixture is subsequently heated to C. over a one-half hour period. Thewater layer is siphoned off and the organic layer again added to 8liters of water. The water-organic layer mixture is thoroughly agitatedwhile heating to 75 C. Thereafter, the water is siphoned off and theorganic layer is thoroughly mixed with 76 grams of attapulgur clay andfilter. The filtrate is 3556 grams of a red-brown liquid which is thedesired acid mixture containing 3.8% by weight phosphorus and 7.01% byweight sulfur.

(b) To a mixture of 1064 grams of mineral oil and 151 grams of zincoxide (3.7 equivalents) maintained at 60 C. in a twelve-liter flaskfitted with a stirrer and reflux condenser, there is added 55 grams of a40% aqueous solution of acetic acid (0.37 equivalent). The resultingmixture is heated to C. and maintained at 90-100 C. for a period of oneand one-half hours during which 3016 grams 3.7 equivalents) of the acidof (a) is added. Thereafter, 75 grams (1.85 equivalents) of zinc oxideis added and this mixture is maintained at --100 C. for one hour. Theresulting product is stripped to a temperature of 150 C. at a pressureof millimeters of mercury over a one and one-half hour period and thenfiltered. The filtrate (3,343 grams) is a reddish-brown oil solution ofthe desired zinc salt analyzing as follows: 2.68% by weight P; 5.54% byweight S; and 4.24% by weight Zn.

EXAMPLE 4 The procedure of Example 3(b) is repeated with thesubstitution of an equivalent amount of a phosphonic acid containingreaction product for the phosphinothioic acid. This product is producedby reacting phosphorus pentasulfide and polybutylene (average M.W. of780) in a mole ratio of 1:125 in the presence of 0.5% by weight sulfurbased on the weight of polybutylene. The reaction mixture is heated at230 C. in a nitrogen atmosphere for about four hours after which thereaction product is diluted with about 1.7 times the weight of thepolybutylene of a mineral oil characterized by a SUS viscosity of 100 at100 F. This diluted mixture is steam-blown at 190 C. for four hours in anitrogen atmosphere. The steamed product is treated with synthetichydrous calcium silicate at C. for three hours and filtered. The productis a clear oil solution of the desired phosphorus acids.

EXAMPLE 5 The procedure of Example 1 is repeated except that anequivalent amount of zinc dioctanoate is substituted for the zincacetate.

While the above examples illustrate the preferred embodiments of thepresent improved process, that is, the preparation of zinc salts usingzinc alkanoate or alkanoic acids as catalyst, it is apparent that byfollowing the indicated procedures, other embodiments of the process canbe practiced. Thus, the zinc oxide can be replaced with barium, calcium,or cadium oxide, hydroxide, or carbonate. Similarly, propionic acid,butyric acid, benzoic acid, their metal salts, and the like may besubstituted for the acetic and octanoic acids and salts of the examples.

The metal salts of this invention are useful as additives in lubricatingoils, gasolines, and fuel oils in the same manner as phosphorus acidmetal salts of the prior art. Particularly useful applications of themetal salts are as extreme pressure agents, detergents, and rust andoxidation inhibiting agents in lubricants. They are also useful asinsecticides, pesticides, ore-floatation agents, plasticizers, etc. Whenused in such applications, the metal salts are eapable of impartingoxidation resistance and anticorrosiveness to the compositions in whichthey are present.

The concentration of the metal salts of this invention in a lubricatingcomposition depends primarily upon the type of oil used and the natureof the service to which the lubricating composition is to be subjected.In most instances, the concentration will range from about 0.001% toabout 5% by weight of the final lubricant. The concentration of themetal salts in a fuel oil or gasoline usually is within the range offrom about 0.000l% to about 1% by weight.

The metal salts of this invention are unique in that they are especiallyresistant to deterioration when they are subjected to high temperatureand prolonged contact with air. This superior stability is an importantquality, especially from the standpoint of the utility of the metalsalts as additives in lubricants, fuel oils, and gasolines. The reasonfor such stability is not understood, but it is known that the stabilityis directly related to the presence of the catalyst in the reactionmixture from which the metal salt is prepared.

The lubricating oils in which the salts of this invention are useful maybe of synthetic, animal, vegetable or mineral origin. Ordinarily,mineral lubricating oils are preferred by reason of their availability,general excellence, and low cost. For certain applications, oilsbelonging to one of the other three groups may be preferred. Forinstance, synthetic polyester oils such as didodecyl adipate anddi-Z-ethylhexyl sebac'ate are often preferred as jet engine lubricants.Normally, the lubricating oils preferred will be fluid oils ranging inviscosity from about 40 SUS (Saybolt Universal Seconds) at 100 F. toabout 200 SUS at 210 F.

The lubricating compositions containing the metal salts of thisinvention may contain also other additives such as, for example,detergents of the ash type, detergents of the nonash type, viscosityindex improving agents, pour point depressing agents, antifoam agents,and auxiliary extreme pressure agents, rust-inhibiting agents, andoxidation and corrosion inhibiting agents.

Ash-containing detergents are exemplified by the oil soluble neutral andbasic salts of alkali or alkaline earth metals with sulfonic acids,carboxylic acids containing at least 12 aliphatic carbon atoms, ororganic phosphorus acids characterized by at least one directcarbon-to-phosphorus linkage such as those prepared by the treatment ofan olefin polymer (e.g., one having a molecular weight of 700100,000)with a phosphorizing agent such as phosphorus trichloride, phosphorusheptasulfide, phosphorus pentasulfide, phosphorus trichloride andsulfur, white phosphorus and a sulfur halide, or a phosphorothioicchloride. The most commonly used salts of such acids are those ofsodium, potassium, lithium, calcium, strontium, and barium. Basic salts,i.e., those in which the metal is present in stoichiometrically largeramounts than the organic acid radical, are especially useful. Thecommonly employed methods for preparing the basic salts involve heatinga mineral oil solution of an organic acid with a stoichiometric excessof a metal base such as a metal oxide, hydroxide, carbonate,bicarbonate, or sulfide at a temperature of around 50 C. and filteringthe resulting mass. The use of a promoter, e.g., a phenol or alcohol, inthe neutralization step to aid the incorporation of a large excess ofmetal is likewise known. A particularly effective method for preparingthe basic salts comprises mixing an acid with an excess of a basicalkaline earth metal neutralizing agent, a phenolic promoter compound,and a small amount of water and then carbonating the mixture at anelevated temperature, e.g., 60 200 C.

Detergents of a non-ash type include 'acylated alkylene polyamines suchas tetraethylene pentamine obtained by 9, reacting the amine with analkenylor alkyl-substituted succinic anhydride or acid having at least50 carbon atoms in the alkenyl or alkyl substituent; the reactionproduct of boric acid with the previously described acyl ated amine; andthe copolymer of parts of betadiethylamino-ethyl acrylate with 95 partsof dodecyl methacrylate, etc.

Antifoam agents include polymeric alkyl siloxanes,poly(alkylmethacrylates) and the condensation product of an alkyl phenolwith formaldehyde and an 'amine. Pour point depressing agents areillustrated by polymers of ethylene, propylene, or isobutene andpoly(alkyl methacrylates). Corrosionand oxidation-inhibiting agentsinclude hindered phenols such as 4-methyl-2,6-di-tert-butylphenol,N,N'-sec-*butyl phenylenediamine, basic metal petroleum sulfates, metalphenates, amines, benzyl thiocyanates, etc. Film strength agentsinclude, e.g., chlorinated petroleum oils containing from 20 to 70% ofchlorine, chlorinated eicosane wax containing from 50 to 60% ofchlorine, hexachloro-diphenyl ether, polychlorophenyl,polychlorobi-phenyl, etc. Oiliness agents include, e.g., methyl oleate,oleic 'acid, stearic acid, sulfurized sperm oil, sperm oil, corn oil,etc. Viscosity index improvers include, e.g., polymerized andcopoly-merized alkyl methacrylates, and polybutene.

The lubricating compositions may be prepared by adding one or more ofthe metal salts of this invention, alone or with other additives, to alubricating oil. In many instances, it is advantageous to prepareconcentrates of the salts of this invention with other additives and tolater add the concentrate to lubricating oil. The following lubricantsare illustrative. (All parts are by weight.)

Example A Parts SAE 30 mineral lubricating oil 93.79 Product of Example1 1.00 Tetraethylene pentamine acylated with 'an equivalent amount ofpolyisobutenyl (average molecular weight=850)-substituted succinic acid5.21 Polymeric alkyl siloxane antifoam agent 0003 Example B SAE W30mineral lubricating oil 87.41 Product of Example 2 2.317 Polymeric,viscosity index improving 'agent (interpolymer of N-vinyl-Z-pyrrolidone(10% by What is claimed is:

1. In the process for preparing metal salts of phosphorus acidscomprising the reaction of a Group II metal base with a phosphorus acidcorresponding to the formula wherein one R is selected from the classconsisting of hydrocarbon, and hydrocarbon-oxy, and XH radicals and theother R is a hydrocarbon radical and X is oxygen or sulfur, theimprovement comprising carrying out the process in the presence of acatalyst selected from the class consisting of carboxylic acids havingup to about 10 aliphatic carbon atoms and salts thereof with a metalselected from the class consisting of Group I metals, Group II metals,aluminum, iron, nickel, cobalt, and copper.

2. The process of claim 1 wherein the Group II metal base is zinc oxide.

3. The process of claim l-wherein the phosphorus acid is aphosphinodithioic acid.

4. The process of claim 1 wherein the catalyst is acetic acid.

5. In the process for preparing metal salts of phosphorus acidsaccording to claim 1 comprising the reaction of from about 1 to 2equivalents of a Group II metal base with 1 equivalent of adialkylphosphinodithioic acid, the improvement comprising carrying outthe process in the presence of a catalytic amount of a carboxylic acidhaving up to about 10 aliphatic carbon atoms.

6. The process of claim 5 wherein the Group II metal base is zinc oxide.

7. The process of claim 5 wherein the carboxylic acid is acetic acid.

8. In the process for preparing metal salts of phosphorus acidsaccording to claim 1 comprising the reaction of from about 1 to 2equivalents of a Group II metal base with 1 equivalent of adialkarylphosphincdithioic acid, the improvement comprising carrying outthe process in the presence of a catalytic amount of a carboxylic acidhaving up to about 10 aliphatic carbon atoms.

9. The process of claim 8 wherein the Group II metal base is zinc oxide.

10. The process of claim 8 wherein the carboxylic acid is acetic acid.

11. In the process for preparing metal salts of a mixture of aphosphorus acid and a hydrocarbon-substituted succinic acid comprisingthe reaction of a Group II metal base with a mixture of 1) organicphosphorus acids corresponding to the formula wherein R is selected fromthe class consisting of hydrocarbon and hydrocarbon-oxy radicals, and Xis oxygen or sulfur, at least one of the acids comprising the mixturebeing other than a phosphorodithioic acid, and (2) ahydrocarbon-substituted succinic acid or anhydride having at least about50 aliphatic carbon atoms in the substituent, the improvement comprisingcarrying out the process in the presence of a catalyst selected from theclass consisting of carboxylic acids having up to about 10 aliphaticcarbon atoms and salts thereof with a metal selected from the classconsisting of Group I metals, Group II metals, aluminum, iron, nickel,cobalt, and copper.

12. In the process for preparing metal salts of a mixture of aphosphorus acid and a substituted succinic acid comprising the reactionof from about 1 to 2 equivalents of a Group II metal base with 1equivalent of a mixture of (l) diarylphosphinodithioic acid and (2) ahydrocarbon-substituted succinic acid having at least about 50 aliphaticcarbon atoms in the substituent, the improvement comprising carrying outthe process in the presence of a catalytic amount of a carboxylic acidhaving up to about 10 aliphatic carbon atoms.

13. The process of claim 12 wherein the diarylphosphinodithioic acid isdi(chlorophenyl)phosphinodithioic acid.

14. In the process for preparing zinc salts of a mixture ofdi(chlorophenyl)phosphinodithioic acid and a substituted succinic acidaccording to claim 12 comprising the reaction of from about 1 to 2equivalents of zinc oxide with 1 equivalent of a mixture ofdi(chlorophenyl)phosphinodithioic acid and a polyisobutene-substitutedsuccinic anhydride wherein the polyisobutene substituent has a molecularweight of about 1000, the improvement comprising carrying out theprocess in the presence of a catalytic amount of acetic acid.

15. A metal salt of a phosphorus acid produced by the process comprisingreacting a Group II metal base with a phosphorus acid corresponding tothe formula wherein one R is selected from the class consisting ofhydrocarbon, hydrocarhon-oxy, and XH radicals and the other R is ahydrocarbon radical and X is selected from the class consisting ofoxygen and sulfur in the presence of a catalyst selected from the classconsisting of car- 'boxylic acids having up to about 10 aliphatic carbonatom and Group II metal salts thereof.

16. A zinc salt according to claim 15 prepared by the process comprisingreacting zinc oxide with said phosphorus acid where the X variables aresulfur in the presence of a catalytic amount of acetic acid.

17. A zinc salt according to claim 15 prepared by the process comprisingreacting from about 1 to 2 equivalents of zinc oxide with 1 equivalentof a diarylphosphin-odithioic acid in the presence of a catalytic amountof a car- 12 boxylic'acid having up to about 10 aliphatic carbon atoms.

18. A zinc salt according to claim 15 prepared by the process comprisingreacting zinc oxide with di(chlorophenyl)phosphinodithioic acid in thepresence of a catalytic amount of acetic acid.

References Cited UNITED STATES PATENTS 2,346,155 4/1944 Denison et a1.260429.9 XR 2,274,302 2/1942 Mulit 260429.9 XR 2,797,238 6/1957 Miller260429.9 XR 2,809,979 10/1957 Craig 260429.9 3,004,996 10/1961 Arakelian 260429.9 3,168,497 2/1965 Twitchett 260429.9 XR 3,238,2483/1966 Rauhut 260429.9 XR 3,271,310 9/1966 Le Suer 260429.9 XR 3,290,34712/1966- Miller 260429.9 3,293,208 12/1966 Milionis 260429.9 XR3,300,409 1/1967 Butler 260429.9 XR

TOBIAS E. LEVOW, Primary Examiner.

H. M. S. SNEED, Assistant Examiner.

